| 초록 |
Two-dimensional materials have attracted strong interest for their fascinating electronic properties and have shown many advantages in optoelectronic applications. Among two-dimensional materials, graphene has demonstrated promising applications in various types of photodetectors from terahertz to ultraviolet, due to light absorption in broad wavelength range and their ultrahigh carrier mobility. However, graphene’s semimetallic nature would give rise to a large dark current (up to 50–100 uA) and low on–off ratio (less than 2). Here, we demonstrate a new method to enhance the on-off ratio of graphene photodetector with metal-graphene-metal structure. In this phototransistor, an asymmetric metal contact (Titanium and Platinum) design is adopted to provide a strong internal electric-field in the phototransistor channel. Optical microscopy and Raman spectroscopy were used to determine optimal etching conditions and observe residues after thermal treatment. The device offers a high photocurrent, a broad spectral bandwidth and compatibility with CMOS technologies. |
